The long -term objectives of the proposed research are to set up well-differentiated rodent and primate parenchymal liver cell cultures; to find the optimal conditions for penetration of these cells by sporozoites of rodent and primate malaria and for the complete pre-erythrocytic development of these parasites; to apply these systems to the production of large quantities of pre-erythrocytic forms and to basic studies of host cell-parasite-interaction in malaria; and to find if it is possible to develop effective experimental vaccines with pre-erythrocytic forms grown in cell culture.